How long should I endure my job?

I am a recent college grad in finance. I worked really hard during school, got good grades and interned for a fancy global company. After graduating I had the though time looking for a job. I accepted a teller position from a credit union out of desperation. I tried to make the best of it but all I have is a list of complaints. I am not the only one, I have made friends from other departments who would vent about the days they have worked as a teller and hated it as well. The credit union I work for seems to experience a lot of turnover and its not just the tellers but higher positions as well. One of our mortgage specialist left after 3 months and one of our central operation specialist left before her 3 month probation.
Added (1). On the 19th I make my 3 months mark. I am certain they will pass me for probation. I am one of their top cross sellers for bank products and they are impressed for my pace as a new teller. With the branch falling apart it would be stupid on their part to lay me off but maybe getting laid off is not a bad thing on my part.
Added (2). @ A Hunch: UBS Internship programs are supposed to last for ONE semester only. The lady I interned for already had a full time assistant. If there was a position open then I would have probably continued working there however I questioned about my personal investments because the rule with financial institutions is you have to surrender your portfolio and abide by UBS employee rules of trading. I have a stock portfolio of $400k and make good side money trading. Working for UBS would have
Added (3). constraints.

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